Improvement in supplying water to air-pumps



UNITEIJ STATES PATENT QFFIGE.

JOHN F. HASKINS, OFI FITGHBURG, MASSACHUSETTS.

`Specification forming part ofLetters Patent No. 117,626, dated August 1, 1871.

To all 'whom t may concern:

Be it known that I, JOHN F. HAsKlNs, of Fitchburg, in the county of Worcester and State of Massachusetts, have invented Improvements in Means for Supplying Water to Air-Compressin g Pumps; and I do hereby declare that the following, taken in connection .with the drawing which accompanies and forms part of this specification, is a description of my invention sufficient to enable those skilled in the art to practice it.

In compressing air it is well known that latent heat contained therein is rendered sensible, and that it has been found necessary to apply to aircompressing pumps, Working rapidly and convstantly, some means for absorbing and conducting off from the pumps the heat so made sensible to prevent the Working parts from injury and expansion. It has been common, heretofore, to introduce water into air-compressing pumps, as closely aspossible to the air-delivery valve, in one of two ways, viz.: First, by a pipe connected with a head of water, and havin g a check-valve to prevent entrance of air into the water-pipe or reservoir; and second, by a pipe connected with a pump worked by positive mechanical devices. In the first of these means the pump has been too much iilled with water, and at times when none is needed and the water ha-s been wasted; for the water Wouldflow into the pump at the time When the piston was making its air-receiving stroke, and as the air-inlet valve opened to admit air water escaped past the valve and ran to waste. Still sufficient was left in excess of the amount needed to greatly diminish the aircompressing capacity of the pump and often to cause the piston to break the pump-head when the quantity of water was so great as to crowd the exit-passage from the pump. For in air-compressing` pumps it is necessary, in order to produce the best results, to have the clearance-space between the compressing-pistou and the deliveryvalve as small as possible; hence the outlet-passages for the compressed air controlled by the delivery-valve are made small and are readily choked by excess of water, and when choked breakage ensues. In the second of the aforesaid old means for supplying water a pump was employed Worked by positive connections, usually a crank or an eccentric, so that the delivery of such water-pump began at nothing and was accelerated to the middle point of the stroke of the pump and then diminished from such point to nothing at the end of the stroke.

In supplying Water to pumps employed in condensing air the supply should be to produce the best efect-one which constantly increases so long as the pressure in the air-condensing pump increases. This result has not been atta-ined hitherto. As the pressure in the air-pump increases so is the heat developed, and the supply of water needs to be given in a constantly-increasing ratio so as to absorb and carry off the constantlyincreasing heat. In compressing a given amount of air of a given temperature to a given density a substantially uniform increase of temperature will be developed, and by experiment or by eX- perience may be determined the proper' amount of water needed to carry off the developed heat, and no more water than such amount should be employed.

By means of my invention, herein to be set forth, it will be seen how such quantity of water will be injected into the pump between its valves with a volume which increases in the ratio with which the pressure in the pump increases, and my invention may be stated as a process, which consists in supplying water to air-compressing pumps between the inlet and delivery valves thereof, in a ratio proportioned practically to the increase of pressure developed in each action of such pumps.

The drawing shows in Figure l, infront elevation, a pair of vertical single-acting air-compressing pumps operated from a driven shaft by cranks placed opposite each other or"one hundred and eighty degrees apart. Fig. 2 shows, in vertical sectional elevation, the apparatus by which I carry into eect my invention of injecting water into the air-compressing pumps in avolume which increases in the same ratio that the pressure increases within each pump. The same apparatus is also shown in elevation in Fig. l as attached and connected to the pumps. Fig. 3 is a copy of a pressure diagram taken from an air-compressing pump, showing the pressures at the different parts of the stroke of the air-pump piston.

a is a piston-rod passing through suitable packing-boxes in each end of each of two cylinders, one, markedv I), being an air-pump, and the other,

...marked c, being a water pump, the latter being worked directly by the former. On the piston-rod al are two piston-heads, d and e, the for- 

